A 2002 Ford Fiesta Ghia key fob remote (to open/close/enable alarm/open boot etc.) is not working. I checked the battery with a multimeter and it was fine but stuck a new one in anyway just in case. No joy. So presumably either the fob transmitter or the receiver is the problem? Any tips on how to DIY diagnose this to narrow the problem down? Is there any way to do a DIY repair once the problem has been identified or do the fob and/or receiver need to be programmed/coded by the experts?